[Solved] Wireless card - bad configuration or faulty hardware?

[dashek]

I have a Lenovo M5400 laptop with rtl8723be wireless card.
Previous user told me that wifi card is probably broken. He has been running Ubuntu on it a few years ago.
And, in fact, wifi does not work. But card is - at least partially - alive.

I'm using ifupdown & wpasupplicant. The symptoms are:

• ifup wlp4s0 ends with dhclient timeout after many attempts to obtain an IP address
• enable_network in wpa_cli goes into slow, infinite loop of "SCAN-STARTED... SCAN-RESULTS... NETWORK_NOT-FOUND..."
• manually scanning for networks with wpa_cli randomly shows all APs, or none

Example:
/etc/wpa_supplicant/wpa_supplicant.conf:

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ctrl_interface=/run/wpa_supplicant
update_config=1
# I've successfully tested it with an USB wireless adapter
network={
	ssid="<my network ssid>"
	psk="<password>"
	mesh_fwding=1
	disabled=1
}

I launch manually wpa supplicant

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wpa_supplicant -B -i wlp4s0 -c /etc/wpa_supplicant/wpa_supplicant.conf

then

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root@hostname:~# wpa_cli
wpa_cli v2.10
Copyright (c) 2004-2022, Jouni Malinen <j@w1.fi> and contributors

This software may be distributed under the terms of the BSD license.
See README for more details.


Selected interface 'wlp4s0'

Interactive mode

>

Everything goes well up to this moment. Then I run the scan:

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> scan
OK
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS
<3>WPS-AP-AVAILABLE
<3>CTRL-EVENT-NETWORK-NOT-FOUND
> scan_results
bssid / frequency / signal level / flags / ssid
6c:ba:b8:8c:8a:10	2462	-16	[WPA2-PSK-CCMP][WPS][ESS]	<my network ssid>

Awesome, let's connect to this AP!

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> enable_network 0
OK
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS
<3>WPS-AP-AVAILABLE
<3>SME: Trying to authenticate with 6c:ba:b8:8c:8a:10 (SSID='<my network ssid>' freq=2462 MHz)
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS
<3>WPS-AP-AVAILABLE
<3>SME: Trying to authenticate with 6c:ba:b8:8c:8a:10 (SSID='<my network ssid>' freq=2462 MHz)
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS
<3>WPS-AP-AVAILABLE
<3>SME: Trying to authenticate with 6c:ba:b8:8c:8a:10 (SSID='<my network ssid>' freq=2462 MHz)
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS
<3>WPS-AP-AVAILABLE
<3>CTRL-EVENT-NETWORK-NOT-FOUND
<3>CTRL-EVENT-SCAN-STARTED
<3>CTRL-EVENT-SCAN-RESULTS   #and so on forever, only the "WPS-AP-AVAILABLE" message doesn't show up anymore

Occasionally, after some time I manage to get apropriate results from 'scan' command. Sometimes it does not work at all just after boot.
I've been browsing the web for solutions for couple of months. Things I've already done:

• [set parameters in /etc/modprobe.d/rtl8723be.conf: ant_sel, fwlps, ips to values other than default (one at a time) and rebooted (after every change)
• checked the journal for firmware related stuff - it's clean.
• checked if this device is suported by firmware-realtek package
• installed firmware-misc-nonfree
• checked if the appropriate firmware is loaded
• taken the laptop apart and checked if antennas are not damaged and connected correctly into wireless adapter
• many other things I forgot to mention

Any ideas what to try next? Maybe just thow the adapter away and buy a new one? What do you think about it?
I can provide more info, just tell me what do you would like to see.

[lewulff]

Question, has the case been opened previously?

My son had a similar type of problem on his AUSU laptop. Turned out the previous owner had left one side of the antenna not connected to the wifi card. He could see Access Points, but never connect to them.

[dashek]

Question, has the case been opened previously?

My son had a similar type of problem on his AUSU laptop. Turned out the previous owner had left one side of the antenna not connected to the wifi card. He could see Access Points, but never connect to them.

No, it hasn't. I'm sure that I connected both antennas correctly.
Also, the problem is the same as before reassembling. So probably this is not an antenna problem.

[Aki]

Hello @dashek,

It would be useful to check:

• whether the regional settings of the wireless card configuration are compatible with those of the wireless access point

• if both the wireless card and the AP are able to transmit using the same WiFi protocol and can use the same WiFi channel

Hope this helps.

[dashek]

Update: I have recently talked with previous owner of this laptop. He had bougth couple of identical Thinkpads. All were running Ubuntu, but mine was the only one having WiFi issues. So I'm almost sure, that it's broken WLAN card. Few days ago I've got an replacement part, but it turned out to not be identical to original. And now I'm battling Lenovo part whitelisting scam.
Since I've found an answer, I'm marking this thread as solved.

But thank you for your reply @Aki

[Aki]

Hello @dashek,
Thanks for updating the discussion.
Good luck with the replacement parts.
All the best.